The Cheyenne River: A Major Missouri Tributary

The Cheyenne River is a significant tributary of the Missouri River, draining a vast area of the northern Great Plains.

Course and Length

It originates in the Black Hills of northeastern Wyoming (near the Thunder Basin National Grassland), flows northeast across the high plains, and enters South Dakota. After passing through the Cheyenne River Indian Reservation and skirting the Badlands, it joins the Missouri River at Lake Oahe near Pierre, South Dakota. Total length: approximately 450 miles (720 km).

Key Features

• Drainage basin: ~24,000 sq mi (62,000 km²), covering parts of WY, SD, MT, NE.
• Major tributaries: Belle Fourche River, Redwater River, Antelope Creek.
• Dams: Angostura Dam (creates Angostura Reservoir) for irrigation and flood control.
• Ecology: Supports prairie wildlife, migratory birds, and warm-water fisheries.

The river's name comes from the Cheyenne people (Dakota: Šahíyena), who historically inhabited the region.